In various applications of electrical power cable, it is necessary to carry electricity from a low pressure region to a high pressure region, or vice versa. For example, electrical submersible pumping systems used in oil wells often contain a seal device, usually referred to as a packer, to isolate one portion of the well from another. Electrical power in these instances must be taken through the packer to energize, for example, a pump motor below the packer. The device for conducting electricity through the packer is usually referred to as a penetrator.
In these environments, the main problem associated with the penetrator is to avoid disruption of the electrical connection due to leakage in the penetrator and exposure of the electrical conductors to oil, brine and other oil well fluids. In addition, these penetrators must be operable over a wide range of temperatures, typically from freezing to 300.degree. F. or more and therefore must absorb stresses from thermal expansion. Likewise, the penetrators typically are exposed to pressure differentials up to 5,000 psi.
While many prior art penetrators are known, they have numerous disadvantages. First many of these prior art devices do not provide adequate sealing against contamination from external fluids, resulting in a degradation of the electrical insulation of the penetrator. In addition, many of these prior art devices are difficult to install in subsea hangers since the subsea hanger is relatively small at its bottom. Moreover, these prior art devices do not provide adequate sealing against oil well fluids leaking out into the environment.
Examples of these prior art devices are disclosed in the following U.S. Pat. Nos. 2,177,508 to Abbott; 2,760,175 to Dunn; 3,197,730 to Hargett; 3,681,739 to Kornick; 3,989,330 to Cullen et al; 4,500,156 to Nguyen; 4,553,807 to Cane; 4,060,299 to Williams; 4,154,302 to Cugini; 4,050,765 to Duesserhoept et al; 4,588,247 to Grappe et al; 4,589,717 to Pottier et al; 4,693,540 to Cane; 4,727,223 to Lee et al; and 4,854,886 to Neuroth the disclosures of which are hereby incorporated herein by reference.